• J
    JamesT

    For reference, the page I was using to investigate the various modes is this one: http://hfradio.org.uk/html/digital_modes.html. Each of the modes has links to an MP3 of the decoding sound.

    posted in High Altitude Balloons read more
  • J
    JamesT

    On further research, the NTX2B (new model) is very linear in frequency with transmit pin voltage, so it should be relatively easy to feed it with the 303's beautiful DAC. JT65 is going to take far too long to transmit, unless we dramatically crush the amount of data we care about. OLIVIA was another one I looked at, which was promising (Bristol use that), but again it's only 2-3 chars per second, and we're never that far out of range (OLIVIA can be picked up from below the noise floor).

    However, there is a mode similar to OLIVIA called PAX2, which gets nearly 12 characters per second out. If that proves to give poor signal, we can try PAX1, which is half as fast.

    ALSO PAX SOUNDS AWESOME http://hfradio.org.uk/PAX2.mp3

    Also Also Bristol school the crap out of us when it comes to HABs - their implementation has always been bare metal, they design their own RF boards and transmit in fancy radio modes. We need to catch up :(

    posted in High Altitude Balloons read more
  • J
    JamesT

    https://ukhas.org.uk/guides:radio_modules:ntx2

    This page seems to indicate we could achieve shifting the frequency by varying the voltage of the input data; which could be happily achieved with a DAC and a pull up network or even just by outputting straight from the DAC. Does that sound good/feasible?

    posted in High Altitude Balloons read more
  • J
    JamesT

    @Phil Do we need anything particular from our radio module, or will the NTX2 and friends be able to handle something like JT65 assuming all the encoding work is done on the processor side?

    posted in High Altitude Balloons read more

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